The present disclosure is directed to an activated sludge sewage disposal system of the type adapted for marine use.
The sewage apparatus consists of a central aeration chamber with aeration orifices located at the bottom. Typically a pair of biological filters along each side are positioned such that aerated sludge is circulated up and into the biological filters. A crossover pipe, connecting the two biological filters, is positioned below the top level of the sludge in the aeration chamber. An exit pipe and anti-syphon vent pipe are connected to the crossover pipe. Th exit pipe goes to the chlorine contact tank through a flexible hose. The chlorine contact tank is a two-section apparatus, the sections being separated by a vertical baffle. The principal novelty, however, appears to reside in the design of the biological filters.
Basically, the filter has a filter medium of a plurality of hollow plastic balls that float on the aerated sludge. This provides contact area for aerobic treatment of the sludge. The buoyant balls are contained by an upper fiberglas grating and a lower fiberglas retention grating. The biological filter allows for both physical and biological filtering.
The following prior patents are pertinent:
______________________________________ 3122594 Kielback 3825119 Rost 3409279 Metrailer 3956128 Turner 3543937 Choun 3966608 Mason et al 3648439 Szczepanski 4159945 Savage ______________________________________
Mason et al (U.S. Pat. No. 3,966,608) discloses a liquid treatment apparatus that has what appears to be an aeration area around impeller 40. Sludge then proceeds through filter media 30 in a recirculating manner. The principal interest revolves around the use of a plastic material for the filter media, using, for example, 3.5 inch Flexirings, having large surface contact area (see col. 2, lines 65 et seq.).
Kielback (U.S. Pat. No. 3,122,594) discloses a contact tower having a bed 25 comprised of spheres or balls 27 (e.g. table tennis balls) contained in the chamber 12 by grids 14 and 16.
Szczepanski (U.S. Pat. No. 3,648,439) discloses a buoyant filter mass having an enclosed area made of parallel rods 33, with the buoyant balls 32 located therein. The other noted references are of general background interest.